Switch



H. KINDLER ETAL Jan. 17, l967 SWITCH 3 Sheets-Sheet 1 Filed March 26, 1964 FIG.I.

uvvsrvrons Helmu'l Kindler 8 Georg Weber ATTORNEYS Jan. 17, 1967 H. KINDLER ETAL SWITCH 5 Sheets-Sheet 2 Filed March 26, 1964 INVENTORS Helmui Kindler 8 Georg Weber W @6 ATTORNEYS SWITCH Filed March 26, 1964 I 5 Sheets-Sheet :5

FIG.3.

INVENTORS Helmu't Kindler 8 Georg Weber BYW @s ATTO RN EYS United States Patent 3,298,237 SWTTQH Helmut iiinrller and Georg Weber, Regensburg, Germany,

assignors to Sachsenwerk Licht und Kraft-Arkhangeseiischait, Munich, Germany Fitted Mar. 26, 19 54, Ser. No. 354,946 Ciaixns priority, application Germany, Apr. 9, 1963,

3 18 Claims. lei. 74-417 The present invention relates to electric switches and, more particularly, to a spring drive for use with electrical switch gear.

There exist switching devices which are equipped with a so-called over-center spring drive. A drive of this type comprises a compression spring one end of which is supported on the frame or casing of the switch, this spring being cocked, i.e., placed under compression, by means of a coupling element which is rotatably mounted on the switching shaft. The spring is cocked to its deadcenter point, and after this dead-center point is passed, the coupling element is mechanically connected to the switching shaft by means of a catch. The switching gear does not have to be latched during the cocking of the spring. This type of drive, however, has the disadvantage that the torque exerted on the switching shaft increases from zero to a maximum, the latter being at tained at the end of the switching movement. This means that, at the beginning of the switch opening movement, a torque is needed which is able to overcome the not insignificant friction involved when the contacts, which are held in closed position by the spring pressure, are separated. This makes it necessary that the angle throughout which a spring cocking member has to be moved becomes quite large. The reason for this is that the drive must be moved so far beyond the dead-center point until the initially very small torque exerted by the spring has attained a value greater than moment of friction. The starting point of the switching movement is therefore not very accurately pin pointed, and depends to a large extent on the magnitude of the frictional forces.

It is, therefore, the primary object of the present invention to provide a switch equipped with a spring drive which overcomes the above drawbacks, and, with this object in view, the present invention resides in an arrangement which incorporates, basically, a cam member which is rotatably mounted on the switch shaft and which has a cam surface provided with a dead-center point. Also provided are spring means, and means for guiding the spring means to press the same into engagement with the cam surface. The spring means are cocked by a cocking device which rotates the cam member to compress the spring means until the same is in engagement with the deadcenter point of the cam surface, whereafter the now-compressed spring means exerts a torque onthe cam member. Additionally, there are means for positively connecting the cam member to the switch shaft after the spring means has engaged the dead-center point of the cam surface. The cam surface is configured to produce an optimal torque relationship between the spring means and the switch shaft throughout the operation of the switch.

Additional objects and advantages of the present invention will become apparent upon consideration of the following description when taken in conjunction with the accompanying drawings in which:

FIGURE 1 is an elevational view of a switch mechanism equipped with a spring drive according to the present invention.

*IGURE 2 is a longitudinal sectional view of the spring drive taken by itself.

FIGURE 3 is a sectional view taken along line I1 and showing the cocking mechanism, the parts being in the position they occupy at the start of a cocking movement prior to the actual switch-opening or switch-closing movement.

FIGURE 3a is a fragmentary sectional view similar to FIGURE 3 but shows the parts in the position they occupy just as the spring has been cocked and takes over the switch-opening (or closing) movement.

FIGURE 4 is a sectional view taken along line II-II and showing the mechanism for positively connecting the cam disc means to the switching shaft, the parts being in the position they occupy at the start of the cocking movement at which no, positive connection is as yet established between the cam member and the shaft.

FIGURE 5 is a sectional view corresponding to FIG- URE 3, but showing a differently configured cam.

FIGURE 6 is a sectional view which also corresponds to FIGURE 3, but shows yet another differently configured cam.

Referring now to the drawings, the same show a drive 1 connected to a switch 3 by means of a bracket 2. The switch 3 may, for example, be the contact mechanism of a circuit breaker or a disconnect switch. The drive 1 comprises two compression springs 4 and 5 which are arranged opposite each other in a guide tube 6. The outer ends bf the springs, i.e., the upper end of the upper spring 5 and the lower end of the lower spring 5, bear against plates '7 which are inserted into slits 8 of the tube 6. The inner end of each spring bears against a mounting block 9, 10, these mounting: blocks being arranged for slidahle movement in the direction of the lengths of the springs. The mounting blocks 9, 10, carry pairs of rollers 11, 12, these rollers being in engagement with two identical cam discs 13, 14, both of which are nonrotatably mounted on a bearing sleeve 15. The bearing sleeve 15 itself is freely rotatable on the main switching shaft 16.

The two cam discs 13 and 14 have the same configuration, namely, a symmetrical figure-eight type configuration, there being, at each end of the figure-eight, a deadcenter nodal point 29 which constitutes the intersection of two cam curvatures.

The cam disc 13 carries two pins 17, 13, which project into arcuate cut-outs 1 and 20 of a coupling member 21 which is a part coacting with the cam disc. The member 21 is non-rotatably secured to the switching shaft by means of a pin 22. The springs are compressed by means of a cooking member 23 which is rotatably mounted on the shaft 16. This cocking member 23 also has two arcuate cut-outs 24 and 25 into which project pins 26 and 27 carried by cam disc 14.

When the switch is in the closed position shown in FIGURE 1, the pins 26 and 27 of cam disc 14 abut against one end of the cut-outs 24 and 25 of cocking member 23,

respectively. If the switch is to be moved to its open position, the cocking member 23 is rotated in the direction represented by the arrows in FIGURES 3 and 4, in any suitable manner, as, for example, by means of a lever 28 which is non-rotatably secured to the cocking member 23. During this movement, the cam disc 14 is carried along due to the interengagement of the cocking member 23 and the pins 26 and 27. The cam disc 13, being non-rotatably connected to the cam disc 14 through the intermediary of the sleeve 15, will of course rotate in unison together with the cam disc 14. Since both cam discs have the same curved configuration for both of the pairs of rollers 11, 12, the two springs 4 and 5 are compressed simultaneously. The nodal point 29 of the cams is reached after the cocking member 23 has been rotated throughout an angle of 90. This position of the parts is shown in FIGURE 3a. Shortly after the cam discs have been turned past the nodal point, i.e., shortly after the pairs of rollers come into engagement with the other portion of the cam curvature, the pins 17 and 18 will be contacted by the ends 19' and 20 of the cut-outs 19 and 20 of the coupling member 21, so that a positive connection is established etween the cam discs and the switching shaft. The springs, which are now in the process of expanding, will,

thanks to the particular configuration of the cam discs,

exert a maximum, high starting moment on the switching shaft. The contacts will be separated quickly and the switch will proceed uninterruptedly to move towards its open position. The torque becomes smaller toward the end of the switch-opening movement. The cocking member 23 will remain in place during this switch-opening movement inasmuch as the pins 26 and 27 are free to move in the cut-outs 24 and 25. These cut-uts are so dimensioned that, in the final open position of the switch, the pins 26 and 27 Will again abut against the ends of the cut-outs.

It will be seen that the above-described arrangement provides two separate lost-motion connections. On the one hand, the pins 17 and 18 of cam disc 13 coact with the cut-outs 19 and 20 of coupling member 21 to provide a lost-motion connection between the spring means and the switch shaft 16 during cocking of the spring means, while the pins 26 and 27 of cam disc 14 coact with the cut-outs 24 and 25 of the cocking member 23 to provide a lost-motion connection between the cocking member and the spring means while the latter rotate the switch shaft.

The switch is closed in a similar manner. That is to say, the springs will be cocked by turning the lever 23, there being no rotational movement of the switching shaft 16 during this cocking because there is no positive or motion-transmitting connection between the springs and the shaft. This connection, however, is establishedin the manner described aboveas soon as the springs have been cocked.

It will be seen that thanks to the above arrangement, the effective torque will be at an optimum through the entire switching operation, both during switch-opening and switch-closing. Furthermore, this result is obtained by making use of the same parts to produce the quick-acting closing and opening movement. Also, thanks to the lostmotion connection afforded by the above-described interengagement between the cam discs and the cocking member, the switch will, once the springs have been cocked, be moved to its open (or closed) position under the influence of the springs, even if the operator holds, and thus prevents rotation of, the cocking member.

FIGURE shows a modified embodiment in which the cam 14a, instead of having the figure-eight configuration of cam disc 14 described above, has a rhombus-like, i.e., generally diamond-shaped configuration, in which the dead-center points 29a are at the acute angles of the cam. This rhombus shape results in a very high torque at the start of the switching movement, which torque rapidly drops to 0.

In the embodiments described above, the cam surfaces are of symmetrical configuration, in that the shapes produce the same torque-versus angular position characteristic during cocking and switching (i.e., switch-opening or switch-closing) movement. The present invention, however, is not limited to the use of such symmetrical cams, since the shape of the cam surface may be altered to produce any desired optimal torque relationship between the springs and the switch shaft throughout the switch-opening and the switch-closing movement. For example, the cam may be so configured that after the initial maximum torque, the torque may decrease gradually, or the torque may remain constant for a substantial portion of the switch-opening (or closing) movement and then decrease toward the end of the switching movement. Alternatively, the configuration of the cam may be such that the torque is substantially constant throughout each phase of the switching operation.

Such an asymmertically configured cam is shown in FIGURE 6 in which the cam 14b has two cam portions 30 and 31 which result in different torque-versus-angular position characteristics during cocking and switching movements. The cam surface portions 31 provide a constant torque during switch-closing movement, while the shape of cam surface portions 30 is such that a high torque is produced at the start of the switch-opening movement in order to overcome the frictional forces arising during separation and to provide adequate acceleration of the movable contact. It will be appreciated that the cocking and switching movement prior to and during switch-closing operation take place while the cam 14b is rotated in clockwise direction, as viewed in FIG- URE 6, so that it will be the cam surfaces 30 which are effective during such cocking prior to the actual switchclosing movement which occurs while the rollers 11, 12, coact with the cam surfaces 31. At the end of this switch-closing movement, the rollers 11, 12, will lie on the cam surfaces 31 in the region of the tips 14b, so that the springs Will not be fully uncocked. The springs are, however, once again fully cocked during the cocking movement prior to the switch-opening movement, during which the cam 14b is rotated in counterclockwise direction so that the rollers 11, 12, while coacting with the cam surfaces 31 which now serve as cocking cams, will be moved away from the center of the cam. The springs will assume their fully cocked position as soon as the rollers 11, 12, reach the dead-center points 2%. From this point on, the springs become uncooked and the switch-opening movement progresses while the rollers 11, 12, move over the cam surfaces 30.

The above-described arrangement incorporating two diametrically opposite spring devices has been found to reduce the bearing friction to a considerable extent, i.e., while the mechanism would be operative with but a single spring device, this would result in relatively high friction. Thanks to the provision of the two oppositely acting spring devices, however, the frictional loss is substantially reduced.

Nor is it absolutely essential, from the point of view of operability, that the cam disc means mounted on the sleeve 15 incorporate two axially spaced apart cam discs 13, 14, but it has been found that the provision of these two individual cam discs, each coacting with one of the two rollers carried by each spring, substantially reduces the wear of the movable parts.

Also, the arrangement of the coupling linkage which power-transmittingly connects the cam disc means with the switching shaft 16 (FIGURE 4) on one side of the cam discs 13, 14, and the cocking linkage for the springs (FIGURE 3) on the other size, allows the mechanism as a whole to be easily assembled.

It will be understood that the above description of the present invention is susceptible to various modifications, changes, and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

What is claimed is:

1. A spring drive for use with a switch having a rotatable shaft, said drive comprising, in combination: a cam member rotatably mounted on the shaft and having a cam surface which has a dead-center point; spring means; means for guiding said spring means to press the same into engagement with said cam surface; cocking means for rotating said cam member to compress said spring means until the same is in engagement with said deadcenter point of said cam surface whereafter the nowcompressed spring means exerts a torque on said cam member; means for positively connecting said cam mernher to the shaft after said spring means has engaged said dead-center point of said cam surface; said cam surface being configured that the force exerted by said spring means, immediately after the same has engaged said deadcenter point of said cam surface, produces a maximum torque on said cam member and hence on the shaft to which said cam member is then positively connected via said connecting means.

2. A spring drive as defined in claim 1 wherein said cam member comprises a disc means whose periphery forms said cam surface; the latter extending over one half of the total periphery of said disc means and said deadcenter point being positioned such that the same is engaged by said spring means after said disc means have been rotated throughout an angle of 90.

3. A spring drive as defined in claim 2 wherein said connecting means comprise pin means carried by and extending laterally of said cam disc means, and a coupling member which is non-rotatably mounted on the switch. shaft, said coupling member being arranged laterally of said cam disc means and having an arcuate cut-out receiving said pin means, said cut-out having such circumferential length that said pin means move in said cut-out during compression of said spring means and engage an end of said cut-out after said spring means have engaged said dead-center point of said cam surface, thereby to provide a lost-motion connection between said spring means and the switch shaft during cocking of said spring means.

4. A spring drive as defined in claim 2 wherein said cocking means comprise pin means carried by and extend ing laterally of said cam disc means and a cocking member rotatably mounted on the shaft and having an arcuate cut-out receiving said pin means; said pin means, in an end position of the switch, being in engagement with an end of said cut-out, and said cut-out having such circumferential length that said pin means move in said cutout during rotation of said cam disc means under the influence of said spring means, thereby to provide a lostmotion connection between said cocking member and said spring means while the latter rotate the switch shaft.

5. A spring drive as defined in claim 4 wherein said cocking means further comprise an actuating member non-rotatably connected to said cocking member.

6. A spring drive as defined in claim 2 wherein said spring means comprise two spring devices arranged diametrically opposite each other and wherein said cam disc means are provided with two identical and diametrically opposite cam surfaces each coacting with a respective one of said two spring devices.

7. A spring drive as defined in claim 6 wherein said cam surface is of symmetrical configuration and has the same torque-versus-angular position characteristic during cocking and switching movements.

8. A spring drive as defined in claim 7 wherein said configuration is of the figure-eight type, there being a deadcenter point at each end of the figure-eight.

9. A spring drive as defined in claim 7 wherein said configuration is a rhombus, there being a dead-center point at each acute angle of the rhombus.

10. A spring drive as defined in claim 6 wherein said surface is of asymmetric configuration and has two portions of different to-rque-versus-angular position characteristics during cocking and switching movements, there being a deadcenter point at the juncture of said cam sur face portions, in consequence of which different torqueversus-angula-r position characteristics are obtained during switch-opening and switch-closing movement.

11. A spring drive as defined in claim 2 wherein said cam disc means comprise two axially spaced apart cam discs having identical cam surfaces and wherein said spring means are provided with two rollers each coacting With a respective one of said two cam discs.

12. A spring drive as defined in claim 1 wherein said guide means comprise a tubular housing within which said spring means is arranged.

13. A spring drive as defined in claim 2 wherein said cam disc means comprise first and second cam discs hav ing identical cam surfaces, said two cam discs being axially spaced apart and non-rotatably mounted on a sleeve which itself is rotatably mounted on the switch shaft; said connecting means comprising first pin means carried by said first cam disc and extending laterally therefrom in a direction away from said second cam disc, a coupling member which is non-rotatably mounted on the switch shaft, said coupling member being arranged laterally of said first cam disc and having a first arcuate cut-out which receives said first pin means, said first cut-out having such circumferential length that said first pin means move in said first cut-out during compression of said spring means and engage an end of said first cut-out after said spring means have engaged said dead-center point of said cam surface, thereby to provide a lost-motion connection between said spring means and the switch shaft during cocking of said spring means; said cocking means comprising second pin means carried by said second cam disc and extending laterally therefrom in a direction away from said first cam disc, and a cocking member rotatably mounted on the shaft and having a second arcuate cut-out receiving said second pin means, the latter, in an 'end position of the switch, being in engagement with an end of said second cut-out, said second cut-out having such circumferential length that said second pin means move in said second cut-out during rotation of said cam discs under the influence of said spring means, thereby to provide a lostmotion connection between said cocking member and said spring means while the latter rotate the switch shaft.

14. A spring drive as defined in claim 13 wherein each of said pin means comprises a plurality of pins, and wherein said coupling member and said cocking member each have a plurality of arcuate cut-outs corresponding in number to the number of pins of said first and second pin means, respectively.

15. A spring drive as defined in claim 14 wherein each of said pin means includes two pins arranged diametrically opposite each other.

16. A spring drive as defined in claim 13, wherein said spring means comprise two spring devices arranged diametrically opposite each other and wherein said first and second cam discs are provided with two identical and diametrically opposite cam surfaces each coacting with a respective one of said two spring devices.

17. A spring drive for use with a switch having a rotatable shaft, said drive comprising, in combination: a cam member rotatably mounted on the shaft and having a cam surface which has a dead-center point; spring means; means for guiding said spring means to press the same into engagement with said cam surface; cocking means for rotating said cam member to compress said spring means until the same is in engagement with said dead-center point of said cam surface whereafter the now-compressed spring means exerts a torque on said cam member; means for positively connecting said cam member to the switch shaft after said spring means has engaged said dead-center point of said cam surface; said cam surface being configured to produce an optimal torque relationship between said spring means and the switch shaft throughout the operation of the switch.

18. A switch comprising, in combination: a contact mechanism having a rotary shaft, and a spring drive coacting with said shaft, said drive comprising a cam member rotatably mounted on said shaft and having a cam surface which has a dead-center point; spring means; means for guiding said spring means to press the same into engagement with said cam surface; cocking means for rotating said cam member to compress said spring means until the same is in engagement with said dead-center point of said cam surf-ace whereafter the now-compressed spring means exerts a torque on said cam member; means for positively connecting said cam member to said shaft after said spring means has engaged said dead-center point of said cam surface; said cam surface being configured that the force exerted by said spring means, immediately after the same has engaged said dead-center point of said cam surface, produces a maximum torque on said cam member and hence on said shaft to which said cam member is then positively connected via said connecting means.

References Cited by the Examiner UNITED STATES PATENTS 330,949 11/ 1885 Wightman 200-68 1,118,692 11/1914 Sone 74'55 1,581,117 4/1925 Haynes 74-54 X 1,807,526 5/1931 Hammerly 20077 X 2,155,594 4/1939 Hart 74527 FOREIGN PATENTS 594,225 5/1959 Italy.

FRED C. MATTERN, ]R., Primary Examiner.

F. E. BAKER, Assistant Examiner. 

1. A SPRING DRIVE FOR USE WITH A SWITCH HAVING A ROTATABLE SHAFT, SAID DRIVE COMPRISING, IN COMBINATION: A CAM MEMBER ROTATABLY MOUNTED ON THE SHAFT AND HAVING A CAM SURFACE WHICH HAS A DEAD-CENTER POINT; SPRING MEANS; MEANS FOR GUIDING SAID SPRING MEANS TO PRESS THE SAME INTO ENGAGEMENT WITH SAID CAM SURFACE; COCKING MEANS FOR ROTATING SAID CAM MEMBER TO COMPRESS SAID SPRING MEANS UNTIL THE SAME IS IN ENGAGEMENT WITH SAID DEADCENTER POINT OF SAID CAM SURFACE WHEREAFTER THE NOWCOMPRESSED SPRING MEANS EXERTS A TORQUE ON SAID CAM MEMBER; MEANS FOR POSITIVELY CONNECTING SAID CAM MEMBER TO THE SHAFT AFTER SAID SPRING MEANS HAS ENGAGED SAID DEAD-CENTER POINT OF SAID CAM SURFACE; SAID CAM SURFACE BEING CONFIGURED THAT THE FORCE EXERTED BY SAID SPRING MEANS, IMMEDIATELY AFTER THE SAME HAS ENGAGED SAID DEADCENTER POINT OF SAID CAM SURFACE, PRODUCES A MAXIMUM TORQUE ON SAID CAM MEMBER AND HENCE ON THE SHAFT TO WHICH SAID CAM MEMBER IS THEN POSITIVELY CONNECTED VIA SAID CONNECTING MEANS. 